Add properties for logging charsets

Add `logging.charset.console` and `logging.charset.file` properties
that can be used to configure charsets for Logback/Log4J2.

Closes gh-23827

spring-boot-project/spring-boot-docs/src/docs/asciidoc/spring-boot-features.adoc

@@ -2204,10 +2204,18 @@ To help with the customization, some other properties are transferred from the S
 | `LOG_DATEFORMAT_PATTERN`
 | Appender pattern for log date format.
 
+| configprop:logging.charset.console[]
+| `CONSOLE_LOG_CHARSET`
+| The charset to use for console logging.
+
 | configprop:logging.pattern.file[]
 | `FILE_LOG_PATTERN`
 | The log pattern to use in a file (if `LOG_FILE` is enabled).
 
+| configprop:logging.charset.file[]
+| `FILE_LOG_CHARSET`
+| The charset to use for file logging (if `LOG_FILE` is enabled).
+
 | configprop:logging.pattern.level[]
 | `LOG_LEVEL_PATTERN`
 | The format to use when rendering the log level (default `%5p`).

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/logging/LoggingSystemProperties.java

@@ -16,6 +16,9 @@
 
 package org.springframework.boot.logging;
 
+import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
+
 import org.springframework.boot.system.ApplicationPid;
 import org.springframework.core.env.ConfigurableEnvironment;
 import org.springframework.core.env.Environment;
@@ -61,11 +64,21 @@ public class LoggingSystemProperties {
 	 */
 	public static final String CONSOLE_LOG_PATTERN = "CONSOLE_LOG_PATTERN";
 
+	/**
+	 * The name of the System property that contains the console log charset.
+	 */
+	public static final String CONSOLE_LOG_CHARSET = "CONSOLE_LOG_CHARSET";
+
 	/**
 	 * The name of the System property that contains the file log pattern.
 	 */
 	public static final String FILE_LOG_PATTERN = "FILE_LOG_PATTERN";
 
+	/**
+	 * The name of the System property that contains the file log charset.
+	 */
+	public static final String FILE_LOG_CHARSET = "FILE_LOG_CHARSET";
+
 	/**
 	 * The name of the System property that contains the rolled-over log file name
 	 * pattern.
@@ -128,6 +141,10 @@ public class LoggingSystemProperties {
 		this.environment = environment;
 	}
 
+	protected Charset getDefaultCharset() {
+		return StandardCharsets.UTF_8;
+	}
+
 	public final void apply() {
 		apply(null);
 	}
@@ -141,8 +158,10 @@ public class LoggingSystemProperties {
 		setSystemProperty(resolver, EXCEPTION_CONVERSION_WORD, "logging.exception-conversion-word");
 		setSystemProperty(PID_KEY, new ApplicationPid().toString());
 		setSystemProperty(resolver, CONSOLE_LOG_PATTERN, "logging.pattern.console");
+		setSystemProperty(resolver, CONSOLE_LOG_CHARSET, "logging.charset.console", getDefaultCharset().name());
 		setSystemProperty(resolver, LOG_DATEFORMAT_PATTERN, "logging.pattern.dateformat");
 		setSystemProperty(resolver, FILE_LOG_PATTERN, "logging.pattern.file");
+		setSystemProperty(resolver, FILE_LOG_CHARSET, "logging.charset.file", getDefaultCharset().name());
 		setSystemProperty(resolver, LOG_LEVEL_PATTERN, "logging.pattern.level");
 		applyDeprecated(resolver);
 		if (logFile != null) {
@@ -170,7 +189,14 @@ public class LoggingSystemProperties {
 	}
 
 	protected final void setSystemProperty(PropertyResolver resolver, String systemPropertyName, String propertyName) {
-		setSystemProperty(systemPropertyName, resolver.getProperty(propertyName));
+		setSystemProperty(resolver, systemPropertyName, propertyName, null);
+	}
+
+	protected final void setSystemProperty(PropertyResolver resolver, String systemPropertyName, String propertyName,
+			String defaultValue) {
+		String value = resolver.getProperty(propertyName);
+		value = (value != null) ? value : defaultValue;
+		setSystemProperty(systemPropertyName, value);
 	}
 
 	protected final void setSystemProperty(String name, String value) {

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/logging/logback/DefaultLogbackConfiguration.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.logging.logback;
 
+import java.nio.charset.Charset;
+
 import ch.qos.logback.classic.Level;
 import ch.qos.logback.classic.encoder.PatternLayoutEncoder;
 import ch.qos.logback.classic.spi.ILoggingEvent;
@@ -87,6 +89,7 @@ class DefaultLogbackConfiguration {
 		ConsoleAppender<ILoggingEvent> appender = new ConsoleAppender<>();
 		PatternLayoutEncoder encoder = new PatternLayoutEncoder();
 		encoder.setPattern(resolve(config, "${CONSOLE_LOG_PATTERN}"));
+		encoder.setCharset(resolveCharset(config, "${CONSOLE_LOG_CHARSET}"));
 		config.start(encoder);
 		appender.setEncoder(encoder);
 		config.appender("CONSOLE", appender);
@@ -97,6 +100,7 @@ class DefaultLogbackConfiguration {
 		RollingFileAppender<ILoggingEvent> appender = new RollingFileAppender<>();
 		PatternLayoutEncoder encoder = new PatternLayoutEncoder();
 		encoder.setPattern(resolve(config, "${FILE_LOG_PATTERN}"));
+		encoder.setCharset(resolveCharset(config, "${FILE_LOG_CHARSET}"));
 		appender.setEncoder(encoder);
 		config.start(encoder);
 		appender.setFile(logFile);
@@ -133,6 +137,10 @@ class DefaultLogbackConfiguration {
 		return FileSize.valueOf(resolve(config, val));
 	}
 
+	private Charset resolveCharset(LogbackConfigurator config, String val) {
+		return Charset.forName(resolve(config, val));
+	}
+
 	private String resolve(LogbackConfigurator config, String val) {
 		return OptionHelper.substVars(val, config.getContext());
 	}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/logging/logback/LogbackLoggingSystemProperties.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.logging.logback;
 
+import java.nio.charset.Charset;
+
 import ch.qos.logback.core.util.FileSize;
 
 import org.springframework.boot.logging.LogFile;
@@ -64,6 +66,11 @@ public class LogbackLoggingSystemProperties extends LoggingSystemProperties {
 		super(environment);
 	}
 
+	@Override
+	protected Charset getDefaultCharset() {
+		return Charset.defaultCharset();
+	}
+
 	@Override
 	protected void apply(LogFile logFile, PropertyResolver resolver) {
 		super.apply(logFile, resolver);

spring-boot-project/spring-boot/src/main/resources/META-INF/additional-spring-configuration-metadata.json

@@ -19,6 +19,16 @@
       "description": "Location of the logging configuration file. For instance, `classpath:logback.xml` for Logback.",
       "sourceType": "org.springframework.boot.context.logging.LoggingApplicationListener"
     },
+    {
+      "name": "logging.charset.console",
+      "type": "java.nio.Charset",
+      "description": "The charset to use for console output"
+    },
+    {
+      "name": "logging.charset.file",
+      "type": "java.nio.Charset",
+      "description": "The charset to use for file output"
+    },
     {
       "name": "logging.exception-conversion-word",
       "type": "java.lang.String",

spring-boot-project/spring-boot/src/main/resources/org/springframework/boot/logging/log4j2/log4j2-file.xml

@@ -9,12 +9,10 @@
 	</Properties>
 	<Appenders>
 		<Console name="Console" target="SYSTEM_OUT" follow="true">
-			<PatternLayout pattern="${sys:CONSOLE_LOG_PATTERN}" />
+			<PatternLayout pattern="${sys:CONSOLE_LOG_PATTERN}" charset="${sys:CONSOLE_LOG_CHARSET}" />
 		</Console>
 		<RollingFile name="File" fileName="${sys:LOG_FILE}" filePattern="${sys:LOG_PATH}/$${date:yyyy-MM}/app-%d{yyyy-MM-dd-HH}-%i.log.gz">
-			<PatternLayout>
-				<Pattern>${sys:FILE_LOG_PATTERN}</Pattern>
-			</PatternLayout>
+			<PatternLayout pattern="${sys:FILE_LOG_PATTERN}" charset="${sys:FILE_LOG_CHARSET}"/>
 			<Policies>
 				<SizeBasedTriggeringPolicy size="10 MB" />
 			</Policies>

spring-boot-project/spring-boot/src/main/resources/org/springframework/boot/logging/log4j2/log4j2.xml

@@ -9,7 +9,7 @@
 	</Properties>
 	<Appenders>
 		<Console name="Console" target="SYSTEM_OUT" follow="true">
-			<PatternLayout pattern="${sys:CONSOLE_LOG_PATTERN}" />
+			<PatternLayout pattern="${sys:CONSOLE_LOG_PATTERN}" charset="${sys:CONSOLE_LOG_CHARSET}"/>
 		</Console>
 	</Appenders>
 	<Loggers>

spring-boot-project/spring-boot/src/main/resources/org/springframework/boot/logging/logback/console-appender.xml

@@ -9,6 +9,7 @@ initialization performed by Boot
 	<appender name="CONSOLE" class="ch.qos.logback.core.ConsoleAppender">
 		<encoder>
 			<pattern>${CONSOLE_LOG_PATTERN}</pattern>
+			<charset>${CONSOLE_LOG_CHARSET}</charset>
 		</encoder>
 	</appender>
 </included>

spring-boot-project/spring-boot/src/main/resources/org/springframework/boot/logging/logback/file-appender.xml

@@ -6,10 +6,10 @@ initialization performed by Boot
 -->
 
 <included>
-	<appender name="FILE"
-		class="ch.qos.logback.core.rolling.RollingFileAppender">
+	<appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
 		<encoder>
 			<pattern>${FILE_LOG_PATTERN}</pattern>
+			<charset>${FILE_LOG_CHARSET}</charset>
 		</encoder>
 		<file>${LOG_FILE}</file>
 		<rollingPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedRollingPolicy">

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/logging/LoggingSystemPropertiesTests.java

@@ -43,6 +43,8 @@ class LoggingSystemPropertiesTests {
 
 	@BeforeEach
 	void captureSystemPropertyNames() {
+		System.getProperties().remove(LoggingSystemProperties.CONSOLE_LOG_CHARSET);
+		System.getProperties().remove(LoggingSystemProperties.FILE_LOG_CHARSET);
 		this.systemPropertyNames = new HashSet<>(System.getProperties().keySet());
 	}
 
@@ -64,6 +66,19 @@ class LoggingSystemPropertiesTests {
 		assertThat(System.getProperty(LoggingSystemProperties.CONSOLE_LOG_PATTERN)).isEqualTo("console pattern");
 	}
 
+	@Test
+	void consoleCharsetWhenNoPropertyUsesUtf8() {
+		new LoggingSystemProperties(new MockEnvironment()).apply(null);
+		assertThat(System.getProperty(LoggingSystemProperties.CONSOLE_LOG_CHARSET)).isEqualTo("UTF-8");
+	}
+
+	@Test
+	void consoleCharsetIsSet() {
+		new LoggingSystemProperties(new MockEnvironment().withProperty("logging.charset.console", "UTF-16"))
+				.apply(null);
+		assertThat(System.getProperty(LoggingSystemProperties.CONSOLE_LOG_CHARSET)).isEqualTo("UTF-16");
+	}
+
 	@Test
 	void fileLogPatternIsSet() {
 		new LoggingSystemProperties(new MockEnvironment().withProperty("logging.pattern.file", "file pattern"))
@@ -71,6 +86,18 @@ class LoggingSystemPropertiesTests {
 		assertThat(System.getProperty(LoggingSystemProperties.FILE_LOG_PATTERN)).isEqualTo("file pattern");
 	}
 
+	@Test
+	void fileCharsetWhenNoPropertyUsesUtf8() {
+		new LoggingSystemProperties(new MockEnvironment()).apply(null);
+		assertThat(System.getProperty(LoggingSystemProperties.FILE_LOG_CHARSET)).isEqualTo("UTF-8");
+	}
+
+	@Test
+	void fileCharsetIsSet() {
+		new LoggingSystemProperties(new MockEnvironment().withProperty("logging.charset.file", "UTF-16")).apply(null);
+		assertThat(System.getProperty(LoggingSystemProperties.FILE_LOG_CHARSET)).isEqualTo("UTF-16");
+	}
+
 	@Test
 	void consoleLogPatternCanReferencePid() {
 		new LoggingSystemProperties(environment("logging.pattern.console", "${PID:unknown}")).apply(null);

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/logging/logback/LogbackLoggingSystemPropertiesTests.java

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.logging.logback;
 
+import java.nio.charset.Charset;
 import java.util.HashSet;
 import java.util.Set;
 
@@ -43,6 +44,8 @@ class LogbackLoggingSystemPropertiesTests {
 
 	@BeforeEach
 	void captureSystemPropertyNames() {
+		System.getProperties().remove(LoggingSystemProperties.CONSOLE_LOG_CHARSET);
+		System.getProperties().remove(LoggingSystemProperties.FILE_LOG_CHARSET);
 		this.systemPropertyNames = new HashSet<>(System.getProperties().keySet());
 		this.environment = new MockEnvironment();
 		this.environment
@@ -94,4 +97,18 @@ class LogbackLoggingSystemPropertiesTests {
 				.containsEntry(LogbackLoggingSystemProperties.ROLLINGPOLICY_MAX_HISTORY, "mh");
 	}
 
+	@Test
+	void consoleCharsetWhenNoPropertyUsesDefault() {
+		new LoggingSystemProperties(new MockEnvironment()).apply(null);
+		assertThat(System.getProperty(LoggingSystemProperties.CONSOLE_LOG_CHARSET))
+				.isEqualTo(Charset.defaultCharset().name());
+	}
+
+	@Test
+	void fileCharsetWhenNoPropertyUsesDefault() {
+		new LoggingSystemProperties(new MockEnvironment()).apply(null);
+		assertThat(System.getProperty(LoggingSystemProperties.FILE_LOG_CHARSET))
+				.isEqualTo(Charset.defaultCharset().name());
+	}
+
 }

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/logging/logback/LogbackLoggingSystemTests.java

@@ -17,6 +17,7 @@
 package org.springframework.boot.logging.logback;
 
 import java.io.File;
+import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
 import java.util.EnumSet;
 import java.util.HashSet;
@@ -30,6 +31,7 @@ import ch.qos.logback.classic.Logger;
 import ch.qos.logback.classic.LoggerContext;
 import ch.qos.logback.classic.spi.LoggerContextListener;
 import ch.qos.logback.core.ConsoleAppender;
+import ch.qos.logback.core.encoder.LayoutWrappingEncoder;
 import ch.qos.logback.core.rolling.RollingFileAppender;
 import ch.qos.logback.core.rolling.SizeAndTimeBasedRollingPolicy;
 import org.junit.jupiter.api.AfterEach;
@@ -564,6 +566,18 @@ class LogbackLoggingSystemTests extends AbstractLoggingSystemTests {
 		assertThat(getRollingPolicy().getFileNamePattern()).isEqualTo(rollingFile);
 	}
 
+	@Test
+	void customCharset() {
+		this.environment.setProperty("logging.charset.console", "UTF-16");
+		LoggingInitializationContext loggingInitializationContext = new LoggingInitializationContext(this.environment);
+		File file = new File(tmpDir(), "logback-test.log");
+		LogFile logFile = getLogFile(file.getPath(), null);
+		initialize(loggingInitializationContext, null, logFile);
+		this.logger.info("Hello world");
+		LayoutWrappingEncoder<?> encoder = (LayoutWrappingEncoder<?>) getConsoleAppender().getEncoder();
+		assertThat(encoder.getCharset()).isEqualTo(StandardCharsets.UTF_16);
+	}
+
 	private void initialize(LoggingInitializationContext context, String configLocation, LogFile logFile) {
 		this.loggingSystem.getSystemProperties((ConfigurableEnvironment) context.getEnvironment()).apply(logFile);
 		this.loggingSystem.initialize(context, configLocation, logFile);